The processing of medical images, for example diagnostic or therapeutic images, typically requires a considerable amount of user interaction. Examples include: acquiring an image, zooming in/out, selecting particular views, selecting particular regions of interest, selecting particular volume slices, selecting particular sub-volumes, applying image processing algorithms and filters, altering presentation parameters such as brightness and false color mapping. When processing an image, the user follows a series of interactions. Preferably, this is standardized to ensure reproducibility and accuracy. However, the series of interactions may be dependent on the needs of the user, the image being processed or even on the preferences of the user. In the context of the invention, image processing means processing images using manual or computer-implemented interactions.
Current medical image viewing applications, such as Picture Archiving and Communication Systems (PACS) and workstations such as Extended Brilliance Workspace (EBW), offer a broad range of viewing and image processing options, which means that the different users performing the same task may produce an acceptable result in different ways. Some standardized views are offered, but this does little to standardize the steps taken during image processing.
A standard series of interaction steps may be defined for particular types of image processing, and the user is instructed to follow these steps for each new image data set; for example, in processing images of hypertrophic male hearts, the steps taken by a radiology consultant may be:                Browsing through the data at planes perpendicular to the longitudinal axes of the heart        Starting from the basis, with the aorta in the lower left corner        Zoom adjusting to fill view with left ventricle        Setting display contrast such that only the myocardium is within the grey value window        Selecting 2 planes at one-third and two-thirds of the ventricle height for display        Measuring using concentric circles tool        Printing out the viewing planes at one-third and two-thirds of the ventricle height        Selecting standard plane number 1        Adjusting levels and adjusting window        Printing out plane number 1        Selecting standard plane number 2        Adjusting levels and adjusting window        Printing out plane number 2        
However, from this example it will be apparent to the skilled person that the actual action taken by the user to carry out these steps may vary considerably, depending on the parameters of the image. For example, in filling the view with the left ventricle, the actual magnification chosen or the size of the zoom selection box is dependent on the magnification at which the original image was acquired. Also the position of the ventricle in the image may vary, forcing the user to zoom and pan, or to draw a zoom selection box at different positions.
The situation is more complicated in practice, because the starting image set may vary depending on, for example, the user's preferences, the modality and the equipment used to acquire the image data set. In addition, the user may wish to vary the procedure, based upon, for example, the user's preference and the contents of the images viewed.
It is known to compare radiological imaging results with a set of expected parameters to detect deviations. “Real-Time Measurement and Audit of Radiation Dose to Patients Undergoing Computed Radiography” by Vano, Fernandez et al, Radiology 2002 225: 283-288; discloses a real-time patient dose monitoring system for auditing computed radiography. Technical data from each exposure and for every examination type are collected and sent by a network to a workstation, which calculates the moving average values of entrance skin dose and dose-area product of the ten most recently examined patients. Comparison of averages with reference values generates warning messages if reference values are exceeded, prompting corrective action if necessary. However, such a comparison system restricts the freedom that users have to perform the procedure, and deviations are presented after the fact.